


Forearms

by EagleHorn



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Ambiguous Gender My Unit | Byleth, Ambiguous Route (Fire Emblem: Three Houses), Angst, F/M, M/M, Post-Timeskip | War Phase (Fire Emblem: Three Houses), Sparring, forearms
Language: English
Status: Completed
Published: 2021-02-22
Updated: 2021-02-22
Packaged: 2021-03-19 07:14:02
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,991
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29622561
Author URL: https://archiveofourown.org/users/EagleHorn/pseuds/EagleHorn
Summary: Byleth is very aware that many of the students have significantly physically changed in the past 5 years. But Seteth should be basically the same, right?So why is he now hanging out at the training grounds when he's never been there before?
Relationships: My Unit | Byleth/Seteth
Comments: 3
Kudos: 26





	Forearms

**Author's Note:**

> Gender-ambiguous Byleth.

Byleth contemplated just how much had changed in the past five years. The years that were one month ago to Byleth. The students that had come back were not just older but were fundamentally different. They had progressed from young adult to adult, without the guidance of their professor. Byleth knew that the students would have soon graduated and gone off into the world, but they would have been able to reach back for help, to ask… and instead Byleth was not there.

Further, the years brought changes to the skills of the group of students. They had honed their abilities based on the last guidance they had received. Byleth was proud at how much progress each student made without their professor’s guiding hand. There were also marked physical changes – not just new hair styles and wardrobes, but broader shoulders, more curvaceous hips, and greater quantities of solid muscle adorned the bodies of Byleth’s students. 

These changes were precisely why Byleth was headed to the training ground. There was a war going on, and Byleth was their General. And any good General needed to know the capabilities of their troops. Byleth’s knowledge was five years out of date. This needed to be fixed. Quickly.

Byleth pushed open the door to the training ground, trying to be as unobtrusive as possible. A good General also knew that their presence could be a distraction. Byleth wanted to observe without influencing. Providing feedback could be tomorrow’s project. 

As Byleth’s eyes swept the room and catalogued its occupants, they settled upon someone not seen here before the war: Seteth. Seteth, who looked the same as ever in his Church of Seiros regalia. Seteth, who had joined Byleth’s class on a mission to visit Flayn’s mother. Seteth, who was very capably wielding an axe against one of the Knights. 

While they had fought together, it was just the once. Byleth did not have a good knowledge of Seteth’s fighting skills. If anything, Byleth was more familiar with Seteth’s stance on proper behavior than his martial abilities. This would be where Byleth would start watching, then. 

Byleth settled down on a bench to watch. Seteth and the knight appeared evenly matched. The knight was perfectly conventional – Byleth noted a reluctance to engage in any “dirty” fighting. A small smile tugged at Byleth’s lips, realizing the thoughts of a mercenary. But Seteth… Seteth’s style was unlike anything Byleth had before seen. Perhaps a mixture of styles? Plus… something archaic? Granted, the axe was not Byleth’s favored weapon, so there may be a school of fighting that Jeralt simply had not taught her. 

After some minutes, the Knight dropped her guard long enough for Seteth to get in a bruising blow that knocked the wind out of her lungs. Seteth extended a hand, which the Knight gladly accepted, pulling her back to her feet. They exchanged pleasantries before she made her way over to a medic for examination. Seteth turned to the bench that had his water flask and noticed Byleth.

“Professor Byleth! I was wondering when I would see you here. Come to get in some training?” He continued to the bench next to Byleth’s, set his axe to the side, and took a long pull from the flask.

“Seteth. I was mostly hoping to observe today. I must say I was quite surprised to see you here. I don’t believe I’ve seen you train before?”

“You have seen me fight.”

“Yes, but just the once. We’ve never sparred. In fact, I’ve never seen you training. Is there a separate training ground reserved for Church officials?”

Seteth responded to the jab with a chuckle. “Not as such, no. It is true that I nearly never sparred while you were teaching here. I was more likely to practice my weapon forms in private than to come down here, with the crowds of students. But now, with the war on…” Seteth shrugged. “It seemed prudent to ensure I was in top fighting shape. So here I am.”

“Indeed, here you are.” Byleth’s head cocked, considering. “Would you be interested in going a round with me?”

A slight pause as he lifted his flask to his lips was the only indication Seteth was anything other than perfectly calm. He eventually settled on, “I thought you said you were here to observe.”

“Mostly observe.” A smile crossed Byleth’s lips, noticing the hesitancy, and guessing at the cause. “Don’t worry, I know how to dial it back. Tell you what. You get to pick my weapon.”

A few moments passed as Seteth considered the offer. Having reached a decision, he stood, tossing Byleth his axe before heading to the weapons racks to grab another for himself. While he was away Byleth shed the less practical parts of the costume that had become standard since the whole merging with the Goddess business and ran through some quick warmups. Setting aside the past five years, it had been some time since Byleth handled an axe. 

Seteth returned with his newly procured weapon. He waited a minute for Byleth to finish warming up before saluting. Byleth returned the salute, then blurred into motion. Even holding back, being able to actually fight, not just sit in meetings, felt *good*. 

During a pause, the pair circled each other. Seteth recognized the tell-tale cock of Byleth’s head that meant the former professor was considering something. “Something on your mind?”

“Just wondering how it is at all practical to fight in that getup. Not only would it be very expensive if damaged, but there are so many areas for a blade to catch.” 

Seteth did not respond with words, instead charging back into the fight. Perhaps purely coincidence, perhaps not, but the next series of blows found Byleth’s blade snagging and ripping some of the fine embroidery of the regalia. Byleth raised her eyebrows suggestively. “Don’t even say it” muttered Seteth. “Pause?” An acquiescing nod answered his question. 

Byleth watched as Seteth rested his axe against the same bench holding his water. He unbuttoned the cuffs, then the buttons down the front, of his jacket, before easing it off his shoulders. In typical Seteth fashion, he fastidiously dusted it off, then folded it neatly before placing his jacket on the bench. 

The sight that met Byleth’s eyes was… unexpected. Seteth wore a thin knit shirt that hugged his torso closely. Byleth was able to see many things that the regalia, while close-fitting, hid. Like muscle definition. The taper from shoulder to waist was not unexpected, but the specific bulges were a sight to behold. 

Seteth had turned so his side, not his back, faced Byleth. This gave Byleth a view of what Seteth did next: push up his sleeves to his elbows. 

As with the torso, Seteth’s regalia allowed one to see the generalities of the advisor’s arms while completely hiding the details. The puffy upper sleeves masked the biceps that strained at the undershirt he wore. And while Byleth academically knew the shape of Seteth’s forearms from the snug lower sleeves, that knowledge paled in comparison to the flesh now exposed. 

Seteth picked up his axe and returned to face Byleth. It was all Byleth could do to not stare at all the little twitches and ripples through Seteth’s forearm as he adjusted his grip on the axe. Seeing Byleth’s intense focus, he assumed his opponent was ready at restarted the fight. His opponent was not ready. Not remotely. But Byleth recovered quickly and rejoined the fight without being decapitated.

When next they circled each other, Byleth risked speech. “Isn’t this far more comfortable than that stiff jacket?”

“It wasn’t a problem when we fought together before.” 

“It was just the once. I wasn’t expecting to be fighting with you as part of my Army on a regular basis. Also, I thought you still hated me.”

Seteth shook his head. “I never hated you. Distrusted you. Didn’t understand what Lady Rhea saw in you. Never hated.”

A shrug came from Byleth’s shoulders. “Same effect to me at the time. I just knew you weren’t part of my team.”

“That is fair. Were it not for Flayn, I might never have learned to trust you.”

“She is a pretty wonderful person.”

The praise of Flayn caused Seteth to glow. He looked about to start gushing her praises when Byleth moved in, disarmed Seteth, knocked him to the ground, and held the axe to his neck. “Yield?”

“Yield.”

Byleth’s axe was immediately replaced by a reaching hand. Seteth accepted, gripping forearm to forearm. It took every ounce of restraint for Byleth to not hold on to that solid piece of muscle any longer than appropriate. The pair moved over to their respective benches to get a drink and stretch. 

“I thank you for the spar, Professor Byleth.”

“Please, just Byleth. Of all people here, I think my Church advisor should be able to stop calling me by a title that always felt weird and is no longer accurate.” 

“As you will. Thank you, Byleth. I hope that this was not a complete waste of your time.”

Byleth repressed a snort. “Seteth, there is no such thing as wasted time when sparring. Even when I am focused on teaching, I have to learn something to be able to teach. And I always learn something about the person I’m sparring against. For example, today I learned you completely drop your guard when Flayn is mentioned. Shouldn’t come up often on a battlefield, but important to know, nonetheless.”

“Hmm,” was Seteth’s only reply. Byleth’s eyes wandered while Seteth seemed to contemplate a more eloquent reply. Seteth’s forearms had taken up so much of Byleth’s focus that the thighs that were also usually hidden by the regalia had escaped notice until now. These were definitely the thighs of a wyvern rider. Solid. Shapely. “Was that the only thing you learned today?”

Byleth’s eyes snapped up. Did Seteth know what thoughts had truly been racing through Byleth’s mind? “Not at all. The Knight you took out earlier could also use some lessons in scrappier fighting. No rules on a battlefield. Honor gets you killed.”

Seteth’s eyes lost focus as he appeared to contemplate this. “And do you plan on teaching her this?”

A noncommittal shrug met the question. “Might be me, might be someone else. But I’ll definitely make sure we include various fighting styles. Speaking of, where did you pick up your style? It seems familiar but… not.”

“Oh, here and there. It is less a formal style than some things picked up over the years.”

“Used to be a traveler? Those are some stories I’d like to hear some day.” An openly curious expression lit up Byleth’s face.

“Some day. Yes. Would you like me to put you weapon away?” There seemed to be some discomfort with the topic that Seteth was deflecting.

“Thank you, Seteth.” Byleth handed over the axe. As Seteth headed over the weapons rack, Byleth watched him, and noticed that his backside was equally distracting to the front. 

Seteth drained the last of the water in his flask. “I suppose this means I am done for today. Thank you, again, for the spar. I look forward to all of the ways in which we work together to end this war.”

Byleth simply nodded in response. Seteth hooked his finger in the collar of his jacket and swung it over his shoulder before heading out of the training grounds. 

Was… was he *sashaying*? Byleth swallowed hard. While he may not have physically changed as much as the students, this was certainly not the Seteth that Byleth knew as a professor. Well, then. 

Knowing some of what lay beneath that regalia was going to make their next war council “interesting”. Byleth turned to face the interior of the training ground once again, choosing a new pair to observe. Or pretend to observe while Seteth’s exit ran on a loop in Byleth’s mind.

**Author's Note:**

> Hi there! Obligatory "hey this is my first fanfic please let me know what you think!!" comment goes here. 
> 
> I'll admit that Setleth isn't really my ship, but there was this Twitter thread on forearms the other day and I couldn't get it out of my head and Seteth was the only person I could see that being not weird with, so here we are.


End file.
